This invention relates to an improvement of an apparatus for plating semiconductor wafers for applying a bump-plating with gold, silver or the like on one surface of the wafers.
In a prior art for plating one surface of a semiconductor wafer, it requires surplus plating steps and materials relating thereto, because in the process a semiconductor wafer to be plated is held with pins at several positions of the periphery of wafer to be dipped in a plating liquid, and it is required to coat a coating such as photoresist, wax or the like on a wafer surface not to be plated and thus to remove the coating from the wafer surface after the plating. Recently, in order to solve the above described disadvantages in the prior art, an apparatus for plating semiconductor wafers has been developed which comprises a plurality of cup-shaped plating basins secured horizontally within a container and a plurality of holders secured in a cover which is movable relative to and above said container, each holder being aligned and engageable with a relevant one of the plating basins to set a semiconductor wafer therebetween, and in which plating liquid is blown up from down to up against the wafers set in the respective basins. However, since in the apparatus the blown up plating liquid tends to turn up to the upside surface of semiconductor wafer, it is necessary that the bottom portion of each holder is formed with an annular nozzle to prevent the upside surface of wafer from contacting with plating liquid by blowing out of a gas through the nozzle. If the blowing of gas is not applied uniformly on the upside wafer surface, plating liquid is apt to turn up and thereby to contact with the wafer surface not to be plated.